1. Field of the Invention
The present invention relates to an improved structure of magnet type sounder of an electronic acoustic alarm mounted on the engine of a car, wherein primarily, a sound emitting circuit board is placed on an acoustic pipe of a supporting plate, and a magnet is held in a housing formed by an encircling plate beneath the supporting plate, and a sound transmitting case is formed as a flare on the bottom portion thereof which is convex in the inward direction to form a spherical dome surface of which an acoustic pipe column is telescopically placed over the acoustic pipe of the supporting plate, this assembly is then placed in a main case body, and further an acoustic resonant lid covers a through hole of the acoustic pipe column of the sound transmitting case, so that an object of volume reducing can be achieved.
2. Description of the Prior Art
A conventional magnet type sounder of an electronic acoustic alarm (referring to FIG. 4) is comprised mainly of the members including a case body A, a sound emitting circuit board B, a magnet C, a sound transmitting seat D and an acoustic resonant lid E etc.. Wherein the sound emitting circuit board B is mounted behind the magnet C, this assembled members are mounted on the sound transmitting seat D provided with a sound transmitting pipe D1, all these are then together placed in the case body A, and the acoustic resonant lid E covers the opening of the sound transmitting pipe D1 of the sound transmitting seat D to induce acoustic resonance for enlarging volume of sound. However, the sound emitting circuit board B therein is mounted behind the magnet C, room is retained solely for mounting of the sound emitting circuit board B, and further, the sound transmitting seat D also needs room, therefore, volume of the case body A can not just be reduced any more. In these days when cars are gradually minimized as well as getting more delicate, room for an engine is relatively narrow and crowded, yet a conventional magnet type sounder of an electronic acoustic alarm has quite a large volume, this makes difficulty and time consuming of assembling or even unability for assembling, in this view, to minimize a magnet type sounder of an electronic acoustic alarm without influencing its volume of sound is a significant subject of studying and development nowadays.